Yeah they've always used mythology (though the NES ones had it all retranslated as Nintendo was anal on anything religious in games) but yeah Square smurfs up some of them and just uses the name for others. Like Bahamut, in Arab mythology he's more closer to being depicted as an aquatic being more then any form of a dragon let alone a flying one who's kind of the dragons/summons, but then again that's not so much Squares fault as they just stole Bahamut from D&D and added some niftyness to him.